1. Technical Field
The present disclosure relates to a tool used to safely open cargo doors, and in particular, to a tool adapted to safely open industrial strength hinged doors of the type commonly found in cargo trucks.
2. Description of the Related Art
Cargo trucks typically include a door at the rear opening of the cargo box to selectively prevent or allow access to the contents carried inside. In the case of industrial cargo trucks used for hauling bulk materials, such as dump trucks, the doors at the rear of the cargo box may be made from heavy duty materials, such as heavy gauge steel, to ensure that contained materials are secure within the cargo box during transport.
FIGS. 8 and 9 illustrate dump truck 100 in a cargo transport configuration (FIG. 8) and a contents-discharging configuration (FIG. 9). In industrial applications, such as in the construction and waste hauling industries, cargo box 110 mounted to dump truck 100 is made from heavy gauge steel such that cargo box 110 can be used to contain, transport and discharge large quantities of heavy bulk materials, such as gravel, building materials, earthen materials, steel and the like. As noted above, these industrial applications may provide a rear door 112 made from a similarly heavy-duty material having comparable strength to the walls and floor of cargo box 110.
In use, dump truck 100 may collect cargo material M within cavity 114 of cargo box 110 at a cargo collection site, such as a raw materials manufacturer. In many cases, material M is loaded from above cargo box 110 using, e.g., a crane, front loader, elevator or other overhead loading device. During such loading from above, rear door 112 of cargo box 110 remains in the closed position shown in FIG. 8 to ensure containment of material M within cavity 114.
With material M contained in cargo box 110 and rear door 112 closed, dump truck 100 can be driven to the delivery site where material M is needed. At the delivery site, cargo box 110 can be elevated to utilize a gravity assist in discharging material M via door 112. Alternatively, cargo box 110 can be lowered from truck 100 by sliding cargo box off of the truck frame while in the elevated configuration of FIG. 9, such that rollers 162 (see, e.g., FIGS. 10 and 12-15) contacting and roll along the ground as cargo box 110 slides away from truck 100.
To discharge material M from cavity 114, door 112 is opened and the front of cargo box 110 is elevated such that cargo box 110 pivots about a pivot point near the rear of cargo box 110 and underneath rear door 112. As shown in FIG. 9, this reconfiguration of cargo box 110 into the discharge position causes material M to dump or fall out of cavity 114. However, material M may also be discharged when cargo box is horizontal as shown in FIG. 8, or when cargo box 110 is on the ground as described above.
In many instances, door 112 is manually opened by an operator at the delivery site. In the case of cargo box 110 shown in FIGS. 8 and 9, rear door 112 pivots about a vertical axis passing through door hinges 116 (FIG. 8). When cargo box is substantially filled with material M, and/or when material M shifts rearwardly during transport, a substantial amount of pressure may build up upon the inner surface of rear door 112. This pressure is released upon the opening of rear door 112, sometimes with significant force and suddenness.
To protect the operator responsible for opening rear door 112, latch mechanism 118 is disposed along sidewall 120 of cargo box 110 such that actuation of latch mechanism 118 is performed out of the swing path (i.e., “door sweep”) of rear door 112 and away from the direction of material discharge from cavity 114. However, the substantial weight of rear door 112, combined with large and occasionally uneven pressures exerted upon rear door 112 by material M, can potentially cause rear door 112 to bind in the closed position even when latch mechanism 118 has been opened. When such binding occurs, the operator must improvise a way to exert additional opening force on rear door 112. In some cases, the operator may place him or herself into the opening path of door 112 and/or the potential discharge flow path of material M in seeking to exert such additional force. In so doing, the worker may expose him or herself to injury.